The present invention relates in general to holding and fixturing devices associated with machining stations, machine tools, processing machines, and workpieces. More specifically the present invention relates to a fixturing device for holding a workpiece which is loaded into an induction hardening machine and which is to be processed by the induction hardening machine while positioned between upper and lower supporting centers. The present invention is described in the context of an induction hardening machine and a workpiece which is mounted between upper and lower centers (i.e., end support shafts). However, the disclosed fixturing device is believed to have broader applicability to a wider range of workpieces and a greater variety of machining centers, machine tools, and processing machines.
One of the considerations in the handling of workpieces is the safety of the machine operator. When workpieces are to be loaded into the machine and unloaded from the machine, it is important that the machine functions be disengaged. When the loading or unloading of the workpiece is completed, the machine functions are then reengaged, such that the operator, and in particular the hand of the operator, is out of harm""s way.
Another consideration in the handling of workpieces is the weight of the workpiece, how the workpiece must be manipulated in order to get it properly positioned and fixtured into the machine, and the repetitive nature of the tasks of loading and unloading workpieces one after another. With the potential for a carpal tunnel injury, or at least carpal tunnel-related problems due to repetitive stress motions, it is desirable to make the handling of the workpiece as simple as possible in order to reduce the potential for injury to the machine operator.
The fixturing device of the present invention, which is specifically configured for holding a shaft-like workpiece, is used in an induction hardening machine. In this specific application, the safety concerns are addressed and the handling of the workpiece is simplified which reduces or minimizes the risk of carpal tunnel injury. The workpiece is ultimately supported between upper and lower shaft-like centers when the induction heating process is performed. However, before the upper center is lowered into position and after it is raised out of engagement with the workpiece, the fixturing device, according to the present invention, holds the workpiece in a proper orientation, not allowing it to tilt in any direction off of its longitudinal axis. By means of the fixturing device, the workpiece is held in a proper orientation so that as the upper center is lowered, there is correct alignment with the workpiece, automatically.
A still further consideration for the design of a suitable fixturing device is its ability to accommodate different sizes of workpieces or at least different sizes of that portion of the workpiece which is held by the fixturing device. As will be described, the fixturing device of the present invention uses a pair of opposed holding blocks to actually contact a cylindrical surface of the workpiece and thereby maintain the workpiece in a true axial orientation. Since the fixturing device is not required to establish full surface contact around the workpiece, a variety of workpiece sizes can be handled without needing to change the fixturing device. Additionally, the holding blocks are spring loaded and configured so as to be movable such that the holding blocks effectively open as the workpiece is inserted and, then through spring tension, close to contact the portion of the workpiece to be held. By properly positioning the fixturing device and making the device balanced and symmetrical on each side of the workpiece, the workpiece is held in a true axial orientation by contact with the holding blocks so that the lowering of the upper center finds the end recess in the workpiece for support of the workpiece during the induction heating and hardening process.
A fixturing device for holding a workpiece for processing by a machine according to one embodiment of the present invention comprises a first subassembly constructed and arranged to be attached to a movable portion of the machine and a second subassembly also constructed and arranged to be attached to the movable portion. The first and second subassemblies are arranged on opposite sides of the workpiece location and each subassembly includes an attachment member, a holding block, connecting means for connecting the holding block to the attachment member with a predetermined spacing therebetween, and spring biasing means for spring loading the holding block at the predetermined spacing. Both the connecting means and the spring biasing means are constructed and arranged to permit movement of the holding block toward the attachment member. The first and second subassemblies are constructed and arranged so that the holding block of the first subassembly and the holding block of the second subassembly are directed at each other and spaced apart so as to define a workpiece-receiving region therebetween
One object of the present invention is to provide an improved fixturing device for holding a workpiece.
Related objects and advantages of the present invention will be apparent from the following description.